want to bring in our pentagon correspondent, barbara starr. what have we learned from this? tell us what happened. >> reporter: well, you know, as you said, right now the intelligence community, the military, has to figure out what they know, what they suspect happened. think of this as csi north korea but not being able to go to the scene of the crime. what they're looking at is that seismic activity and trying to work their way backwards as to what happened. they believe now that this was, of course, an underground nuclear test, possibly several kilotons. but they need to get better analysis, they need to get air sampling, see what is now released into the atmosphere, and try and assess from all of that what happened. once they know that, the next set of questions, the next part of the investigation, how did north korea pull it off? where did they get help? did they get help? did they have the technology, the engineering expertise, fabrication to really do there is? and finally if they really did it, and it is a miniaturized test, as they claim, that's a huge concern that